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lunedì 6 febbraio 2023

# gst: multiphase transitions and existence of bistable modes; how morphoelastic donuts get their wrinkles

<< Many biological structures are toroidal, or donut shaped. These structures often contain intricate wrinkling patterns that change as the object grows or contracts. >>

<< The team found that toroidal structures with large holes typically develop surface wrinkles close to the hole, whereas ones with smaller holes tend to form them away from the hole. Additionally, soft structures often have localized dimples, while stiff ones have bidirectional stripes or a mixture of spiral and axisymmetric stripes. Lastly, moderate-stiffness structures are typically adorned with periodic hexagonal patterns or a combination of hexagonal and labyrinth-like patterns. (AA) also found that their theory can predict wrinkling patterns in some nontoroidal structures, suggesting that it could be applied to a diverse range of objects. >>

Ryan Wilkinson. How Nature’s Donuts Get Their Wrinkles. Physics 16, s5. Jan 25, 2023. 

T. Wang et al. Curvature-regulated multiphase patterns in tori. Phys. Rev. Lett. 130, 048201. Jan 25, 2023.

Also

keyword 'transition' | 'transitional' in FonT



keyword 'transition' | 'transizion*' in Notes (quasi-stochastic poetry)




Keywords: gst, morphogenesis, transitions, multiphase transitions, bistability, pattern formation, elastic deformation, mechanical deformation




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martedì 31 gennaio 2023

# gst: analogy between streamers in sinking spheroids, gyrotactic plumes and chemotactic collapse (when a plume structure blows up when a parm is above a threshold)

<< In a dilute suspension where sinking spheroids or motile gyrotactic microorganisms are modelled as orientable and negatively buoyant particles, (AA) have found analytical solutions to their steady distributions for a given parallel flow profile. The coupling between their distribution and the vertical flow is nonlinear, enabling the uniform base state to bifurcate into a structure reminiscent of the streamers in settling spheroid suspension and gyrotactic plume. This bifurcation depends on a single parameter that is proportional to the average number of particles on a horizontal cross section. In a three-dimensional axisymmetric system, the plume structure blows up when the parameter is above a threshold. (AA) discuss how this singularity is analogous to the chemotactic collapse of a Keller-Segel model, and the significance this analogy entails. >>

Lloyd Fung. Analogy between streamers in sinking spheroids, gyrotactic plumes and chemotactic collapse. arXiv: 2301.07164v1 [physics.flu-dyn]. Jan 17, 2023.

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keyword 'collapse' in FonT

keyword 'spheroids' in FonT

Keywords: gst, analogy, spheroids, collapse, chemotactic collapse 


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lunedì 30 gennaio 2023

# gst: towards the characterization of lines, links, writhes and twists in a vortex.


<< Vorticity in turbulent flows is often organized into complex geometries that influence the dynamics. (AA) use a relatively novel approach to describe these geometries: that of obtaining segments of vortex lines embedded in the flow. This enables to quantify the geometric features of these objects. >>

<< Vortex lines differ widely in their behaviour but (AA) find some unifying features. The decay from high levels of vorticity is shown to happen over a short fraction of the vortex length. The local curvature is inversely related with the vorticity magnitude. Strong parts of vortex lines bundle together. >>

Saumav Kapoor, Rama Govindarajan, Siddhartha Mukherjee. Geometric characterization of vortex lines in turbulence. arXiv: 2301.06808v1 [physics.flu-dyn]. Jan 17, 2023.

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keyword 'vortex' in FonT


keyword 'vortice' in Notes
 (quasi-stochastic poetry)


Keywords: gst, vortex, vortices, vortexes, vorticity



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sabato 21 gennaio 2023

# chem: spontaneous reconfiguration of deformable nanoparticles (in response to environmental cues)


<< Deformable nanoparticles (NPs) offer unprecedented opportunities as dynamic building blocks that can spontaneously reconfigure during assembly in response to environmental cues. >>

<< deformable spherical NPs of radius 50 nm whose surface is tailored with octahedrally distributed charged patches and double-cap charged patches adapt their shape differently in response to changes in surface charge coverage and ionic strength. >>

AA << find shape transitions to rounded octahedra, faceted octahedra, faceted bowls, oblate spheroids, spherocylinders, dented beans, and dimpled rounded bowls. >>

AA << demonstrate that similar shape transitions can be achieved in deformable NPs of different sizes. >>️

Fanbo Sun, Nicholas E. Brunk, Vikram Jadhao. Shape control of deformable charge-patterned nanoparticles. Phys. Rev. E 107, 014502. Jan 10, 2023.


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keyword 'self-assembly' in FonT


keyword 'nano' in FonT


keyword 'nano' in Notes 
(quasi-stochastic poetry)


Keywords: chem, nano, nanoparticles,  NPs, self-assembly, colloids, polymers, vesicle structures.


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giovedì 19 gennaio 2023

# gst: an approach to information content in the music of J. S. Bach

<< Music has a complex structure that expresses emotion and conveys information. Humans process that information through imperfect cognitive instruments that produce a gestalt, smeared version of reality. What is the information that humans see? And how does their perception relate to (and differ from) reality? To address these questions quantitatively, (AA) analyze J. S. Bach's music through the lens of network science and information theory. >>

They << find that Bach's music is structured for efficient communication; that is, it communicates large amounts of information while maintaining small deviations of the inferred network from reality. >>

They << probe the network structures that enable this rapid and efficient communication of information -- namely, high heterogeneity and strong clustering. (..) More generally, (they) gain insight into features that make networks of information effective for communication. >>

Suman Kulkarni, Sophia U. David, et al. Information content of note transitions in the music of J. S. Bach. arXiv: 2301.00783v1 [physics.soc-ph]. Jan 2, 2023. 

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keyword 'music' in FonT


keyword 'jazz' in FonT


keyword 'jazz' in Notes 
(quasi-stochastic poetry)


Keywords: gst, music, jazz, information theory, note transitions, Bach








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lunedì 16 gennaio 2023

# gst: diffusivity of ordered and freely evolving bubbly suspensions.

AA << investigate the dispersion of a passive scalar such as the concentration of a chemical species, or temperature, in homogeneous bubbly suspensions, by determining an effective diffusivity tensor. Defining the longitudinal and transverse components of this tensor with respect to the direction of averaged bubble rise velocity in a zero mixture velocity frame of reference, (AA) focus on the convective contribution thereof, this being expected to be dominant in commonly encountered bubbly flows. >>

<< In the limits of low and of high Péclet number, including inertial effect of the flow does not affect the scaling of the effective diffusivity with respect to the Péclet number. These results are confirmed by direct numerical simulations performed in different flow regimes, for spherical or very deformed bubbles and from vanishingly small to moderate values of the Reynolds number. Scalar transport in arrays of freely rising bubbles is considered by us subsequently, using numerical simulations. In this case, the dispersion is found to be convectively enhanced at low Péclet number, like in ordered arrays. At high Péclet number, the Taylor dispersion scaling obtained for ordered configurations is replaced by the one characterizing a purely mechanical dispersion, like in random media, even if the level of disorder is very low. >>️

Aurore Loisy, Aurore Naso, Peter D. M. Spelt. The effective diffusivity of ordered and freely evolving bubbly suspensions. arXiv:2301.00028v1 [physics.flu-dyn]. Dec 30, 2022. 

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keyword "bubble" in FonT


keyword "bolla" | "bolle" in Notes (quasistochastic-poetry): 



Keywords: gst, bubble, bubbly suspensions, diffusion, fluctuation




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Etichette: , , , ,

sabato 14 gennaio 2023

# gst: approaching chaotic dynamics to trace the complexity of rough nanostructured surfaces

AA << use the basic ingredients of chaotic dynamics (stretching and folding of phase space points) for the characterization of the complexity of microscopy images of rough surfaces. The key idea is to use an image as the initial condition of a chaotic discrete dynamical system, such as the Arnold cat map, and track its transformations during the first iterations of the map. Since the basic effects of the Arnold map are the stretching and folding of image texture, the application of the map leads to an enhancement of the high frequency content of images along with an increase of discontinuities in pixel intensities. (AA) exploit these effects to quantify the complexity of S type (lying between homogeneity and randomness) of the image texture since the first (enhancement of high frequencies) can be used to quantify the distance of texture from randomness and noise and the second (the proliferation of discontinuities) the distance from order and homogeneity. The method is validated in synthetic images which are generated from computer generated surfaces with controlled correlation length and fractal dimension and it is applied in real images of nanostructured surfaces obtained from a scanning electron microscope with very interesting results. >>️

A. Kondi, V. Constantoudis, P. Sarkiris, K. Ellinas, and E. Gogolides. Using chaotic dynamics to characterize the complexity of rough surfaces. Phys. Rev. E 107, 014206. Jan 11, 2023. 


Also

Able to track changes in noise. 
(quasi-stochastic poetry) 
Notes. Sep 13, 2007. 

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keyword 'chaos' | 'chaotic' in Font



keyword 'caos' | 'caotico' in Notes (quasi-stochastic poetry)



Keywords: gst, chaos, chaotic, nano, roughness, wetting, surfaces, etching scanning 


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